1. Field of the Invention
The present invention relates generally to a tamper monitoring article, system and method of use. In particular, the invention relates to a seal article that is operable to self monitor its integrity and to indicate, actively or passively, when its integrity has been or is being reduced or compromised.
2. Discussion of Related Art
From time to time it has been desirable not only to lock items or secure the items in some fashion, but also to determine whether the lock or security of the item has been breached or that the item has been tampered with. At one time, a person wanting to write a confidential letter would employ a wax seal to close the letter, and would emboss the seal with a difficult-to-reproduce pattern or imprint. A recipient of the letter would know if the letter had been opened and read by the integrity of the embossed wax seal. If the seal was intact, the recipient could reasonably conclude that the letter had not been tampered with since sealing. But, the wax seal was easy to defeat, and did not work sufficiently well in applications outside of sealing paper documents, such as in lock-type applications.
Seals made of non-wax materials, especially malleable metals that were more robust than wax, were employed subsequently. These metal seals could be made into self-fastening strips, and then could be used in combination with locks to determine whether the locks had been opened during some interim period. While more robust than wax, the metal seals were also insufficient for some applications. The seals were too easy to defeat, and were unable to be sufficiently monitored during use.
To address the issue of monitoring, a loop of wire was run through a sealing device, the loop ends started and ended at a monitor. The sealing device was configured so that if the integrity of the sealing device was compromised, the continuity of the wire loop was reduced or eliminated. The monitor checked the continuity of the wire. Thus, a break in the wire loop would result in a break in the wire continuity, which was detected by the monitor. Accordingly, the sealing device integrity could be monitored.
A fiber optic seal having a fiber optic bundle and a locking device for the free ends of the fibers in the bundle was used to determine whether a secure installation remained unpenetrated over a period of time. The random arrangement of fibers in each bundle offered an added measure of security in that it was difficult to reproduce an exact replica of the random fiber pattern using a replacement bundle of fibers. As before, removal, tampering or otherwise destroying the sealing device had the effect of manipulating or breaking the fibers which would result in a detectable change in the fiber optic bundle.
U.S. Pat. No. 4,883,054 to Fuller et al. discloses an apparatus for detecting a break in an optical fiber that can transmit laser light. The fiber communicates with a laser light detector, which can detect a break in the fiber or a change in the laser light transmission. Thus, it is possible to monitor the integrity of an optical fiber, and detect breaks or changes in the fiber.
A tripwire and a magnetic circuit technique can detect continuity of a circuit in other electronic sealing devices. The circuit continuity is monitored and communicated to an associated radio frequency identification device (RFID). A break in the circuit can cause the RFID to signal an associated RFID monitor that there was a break in the continuity of the circuit. Thus, unauthorized openings of containers can be detected and communicated via RFID.
For applications that have increased volumes or numbers of containers, such as transporting luggage bags through airports, it can be problematic to attach currently available sealing devices to as many container openings as might be desirable. While some commercially available sealing devices may be convenient to use, such as those devices having a pressure sensitive adhesive for attaching strap ends together, those sealing devices may be too easily circumvented. For example, some pressure sensitive adhesives are known to lose adhesivity at temperature extremes. Thus, freezing or heating the pressure sensitive adhesive not only allows the sealing device to be removed without breaking a continuity circuit, but may also allow replacement of the same seal device after the unauthorized entry into the sealed container leaving no evidence of an unauthorized entry.
In the field of radio frequency identification devices (“RFID”), communication systems have been developed utilizing relatively large packages. These relatively large electronic packages have been affixed, for example, to railroad cars to reflect radio frequency (RF) signals in order to monitor the location and movement of such cars. As with most electronic applications, the size of such devices has decreased over time. Other, smaller RFID packages have been developed for applications in the field of transportation and logistics, examples include automobile and library book tracking. These packages include passive or reflective systems of the type produced by Amtech Inc. (Dallas, Tex.).
In still other applications of article location and tracking, such as in the postal service or in the field of airline baggage handling and transport, it has become practical and feasible to use RFID devices on smaller articles of transport such as letters, boxed mail shipments and airline luggage.
Alternatives to RFID device tracking and monitoring include bar code identification and optical character recognition (OCR) techniques. Bar code identification and OCR techniques are labor intensive and may, for example, require physical manipulation of the article and/or bar code readers to read these bar codes before the transported article reaches its final destination. In addition, the cost of bar code readers and optical character readers can be prohibitive thus reducing the number of locations at which these readers can be used. Furthermore, both bar code readers and optical character readers are sometimes insufficiently reliable.
In the fields of animal tracking, other types of passive RFID tags have been developed by Hughes, Inc., a subsidiary of Destron Corporation (Irvine, Calif.). These tags utilize a coil wrapped around a ferrite core. Such passive RFID tags have an undesirably limited range, on the order of about 23 centimeters (9 inches), have undesirably limited data handling capability, and are difficult or impossible to program in a field environment. Other disadvantages of the tags can include undesirably limited data storage capacity, and the speed of operation.
Accordingly, it would be desirable to have a signaling device with at least some improved properties relative to the currently available options for tracking, monitoring and signaling devices and techniques.
It would be desirable to have a security article having improved properties. For example, such properties might include ease of use and cost economy. Other desirable properties might include an additional level of security or an increased tamper resistance.